1. Field of the Invention
The invention relates to wrapping a load with packaging material, and, more particularly, to stretch wrapping.
2. Description of the Related Art
Various packaging techniques have been used to build a load of unit products and subsequently wrap them for transportation, storage, containment and stabilization, protection and waterproofing. One system uses stretch wrapping machines to stretch, dispense, and wrap stretch packaging material around a load. Stretch wrapping can be performed as an inline automated packaging technique which dispenses and wraps packaging material in a stretched condition around a load on a pallet to cover and contain the load. Pallet stretch wrapping, whether accomplished by turntable, rotating arm, or rotating ring typically covers the four vertical sides of the load with a stretchable film such as polyethylene film. In each of these arrangements, relative rotation is provided between the load and a packaging material dispenser to wrap packaging material about the sides of the load.
Wrapping packaging material about the sides of the load typically unitizes and stabilizes the load. However, such side wrapping generally does not cover the top of the load or secure the load to the pallet in a manner which would promote increased stability. Because the structure of typical stretch wrap apparatus, it is difficult to wrap packaging material about the top and bottom of the load to secure the load to the pallet for stability. Previous attempts to wrap packaging material about the top and bottom of a load include holding a palletized load on the tines of a forklift truck, and placing the load and tines supporting the load within a wrapping mechanism to be wrapped. This method required the driver of the forklift truck to carefully control the timing and position of the truck and the wrapping machinery revolving around the load and tines of the forklift truck to wrap packaging material about the top and bottom of the load to avoid undesirable interference between the truck, the load and the wrapping machinery during wrapping.
Alternatively, the top and bottom of a load have been wrapped by conveying a load through a wrapping ring on a conveying mechanism, such that after wrapping, the load is "wrapped" to the conveyor, and the conveyor must move the load and the packaging material away from the wrapping area. Such devices are expensive, requiring structure to keep the load and the packaging material moving at the same speeds along the conveyor, preventing the packaging material from being caught or torn, and arrangements to get electrical power to the rotating portion of the ring for controlling the dispenser mounted on the ring.
In light of these drawbacks, there is a need to wrap the top and bottom of a load with packaging material in a simple, reliable, and inexpensive manner.